A facile self-assembly approach to prepare macroscopic graphite oxide (GO) membranes at a liquid/air interface by evaporating the hydrosol of graphene oxide was proposed. GO was synthesized from natural graphite powder by a modified Hummers method. An atomic force microscopy (AFM) image show that the thicknesses of the graphene oxide layers are within a very narrow range of 1.1-1.2 nm. The results also show that water-dispersed graphene oxides re-assemble into a layer-by-layer macroscopic structure. The GO membranes could be formed over relatively broad temperature and graphene oxide concentration ranges. It is also found that the thicknesses and size of the membranes can be controlled by adjusting the assembly period and the liquid/air interface area provided by the container for membrane formation.